1. Field of Invention
The present invention relates to a capacitor, a semiconductor device including a capacitor or a MIS (Metal-lnsulator-Semiconductor)-type semiconductor device, an electro-optic device using the semiconductor device as an active matrix substrate, a method of manufacturing a capacitor, a method of manufacturing a semiconductor device, and an electronic apparatus. More specifically, the present invention relates to a technique for forming an insulating layer used for an electric element.
2. Description of Related Art
A technique for forming a capacitor on a substrate in any one of various semiconductor devices, generally includes laminating a lower electrode, an insulating layer as a dielectric layer, and an upper electrode in that order. In this case, a silicon oxide film or a tantalum oxide film is used as the insulating film. Of these oxide films, the silicon oxide film with high voltage resistance is formed in the related art by a method in which a silicon film is thermally oxidized at a temperature of about 1000xc2x0 C. to 1300xc2x0 C.
Of various semiconductor devices, each of a MIS diode and a thin film transistor (hereinafter xe2x80x9cTFTxe2x80x9d) includes a MIS section, which includes a metal layer, an insulating layer and a semiconductor layer. As the insulating layer, a silicon oxide film obtained by thermally oxidizing a surface of a silicon film used as a semiconductor layer at a temperature of about 1000xc2x0 C. to 1300xc2x0 C. has high voltage resistance.
A tantalum oxide film has the advantage of a high dielectric constant, but formation of the tantalum oxide film by anodization requires feed wiring for anodization, thereby causing a problem of significantly decreasing the degree of design freedom of a semiconductor device including TFT, and the like formed on the same substrate. Also, the tantalum oxide film can be obtained by thermally oxidizing a tantalum film in the air at room temperature. However, such a tantalum oxide film has a problem of low voltage resistance.
The method of forming an insulating film at a high temperature of over 1000xc2x0 C. has a problem in which an inexpensive substrate of glass or the like cannot be used as a substrate.
Furthermore, when aluminum wiring is formed on the substrate, treatment at a high temperature has the problem of failing to form the aluminum wiring because a treatment temperature of over 1000xc2x0 C. exceeds the heat resistant temperature of the aluminum wiring.
The present invention provides a capacitor including an insulating layer having high voltage resistance even when it is formed at a relatively low temperature, a semiconductor device including the capacitor, an electro-optic device including the semiconductor device as an active matrix substrate, an electronic apparatus using the electro-optic device, a method of manufacturing a capacitor, and a method of manufacturing a semiconductor device.
The present invention provides a semiconductor device including a MIS section with high voltage resistance, which can be formed at a relatively low temperature, an electro-optic device including the semiconductor device as an active matrix substrate, an electronic apparatus using the electro-optic device, a method of manufacturing a capacitor, and a method of manufacturing a semiconductor device.
In order to address or achieve the above, a capacitor of the present invention includes a lower electrode, an insulating layer, and an upper electrode, which are laminated in that order. The insulating layer includes an oxide film formed by high-pressure annealing oxidation of an insulating layer-forming metal film under high pressure in an atmosphere containing water vapor.
In the present invention, the insulating layer may include only the oxide film or a multilayer structure including the oxide film and another insulating film.
In the present invention, a method of manufacturing a capacitor including a lower electrode, an insulating layer and an upper electrode includes forming a insulating layer-forming metal film, oxidizing the insulating layer-forming metal film by high-pressure annealing under high pressure in an atmosphere containing water vapor to form an oxide film which is used as the insulating layer or a part of the insulating layer.
In the present invention, high-pressure annealing is performed, for example, at a temperature of 600xc2x0 C. or less. For example, high-pressure annealing is performed at a temperature of 300 to 400xc2x0 C. under a pressure of 0.5 MPa to 2 MPa.
In the present invention, the insulating layer-forming metal film includes a tantalum (Ta) film or a tantalum alloy film.
In the present invention, the insulating layer of the capacitor contains the tantalum oxide film produced by high-pressure annealing, and thus has high voltage resistance. In the present invention, the tantalum oxide film is formed by high-pressure annealing, not by anodization, and thus feed wiring for anodization is not required. Therefore, a semiconductor device including TFT and the like formed on the same substrate has a high degree of design freedom. Furthermore, the tantalum oxide film having high uniformity can be obtained because of treatment under pressure. There is also the advantage that many substrates can be simultaneously treated. Furthermore, the temperature sufficient for high-pressure temperature is 600xc2x0 C. or less, particularly 300xc2x0 C. to 400xc2x0 C., and thus no trouble occurs in use of a glass substrate as the substrate. Even if aluminum wiring is formed, high-pressure annealing under the temperature condition does not deteriorate the aluminum wiring unless the aluminum wiring is exposed from the surface of the substrate.
In the present invention, at least the insulating layer side of the lower electrode may include the same metal as, or a different material from, the insulating layer-forming metal film.
The capacitor having the above construction can be manufactured by a method in which only the surface of the insulating layer-forming metal film is oxidized by high-pressure annealing to form the oxide film used as the insulating layer or a part of the insulating layer, the remainder of the insulating layer-forming metal film being used as the lower electrode or a part of the lower electrode, or a method in which the lower electrode is formed below the insulating layer-forming metal film, and the insulating layer-forming metal film is entirely oxidized by high-pressure annealing to form the oxide film used as the insulating layer and a part of the insulating layer.
In the present invention, after high-pressure annealing, annealing is preferably performed under atmospheric pressure or low pressure. Such annealing can remove or substantially remove moisture contained in the tantalum oxide film to enhance crystallinity, thereby further enhancing voltage resistance.
The capacitor of the present invention is suitable to form a semiconductor device including other semiconductor elements formed on the same substrate. An example of such a semiconductor device is an active matrix substrate used for an electro-optic device, such as an active matrix liquid crystal device or the like. In the active matrix substrate, the capacitor of the present invention is used as, for example, a storage capacitor in each pixel.
In another aspect of the present invention, a semiconductor device includes a MIS semiconductor element formed on a substrate, and including a MIS section, which includes a metal layer, an insulating layer, and a semiconductor layer. The insulating layer includes an oxide film formed by high-pressure annealing oxidation of an insulating layer-forming metal film under high pressure in an atmosphere containing water vapor.
In the present invention, a method of manufacturing a semiconductor device including a MIS semiconductor element, which is formed on a substrate, and which includes a MIS section including a metal layer, an insulating layer, and a semiconductor layer, includes forming an insulating layer-forming metal film, and then oxidizing the insulating layer-forming metal film by high-pressure annealing under high pressure in an atmosphere containing water vapor to form an oxide film used as a part of the insulating layer.
In this method, high-pressure annealing is performed, for example, at a temperature of 300xc2x0 C. to 400xc2x0 C. under a pressure of 0.5 MPa to 2 MPa.
In the present invention, the insulating layer of the MIS section includes a tantalum oxide film formed by high-pressure annealing, and thus has high voltage resistance. Furthermore, the temperature sufficient to provide high-pressure annealing is 300xc2x0 C. to 400xc2x0 C., thereby causing no trouble in use of a glass substrate as the substrate. Even if aluminum wiring is formed, high-pressure annealing under the temperature condition does not deteriorate the aluminum wiring unless the aluminum wiring is exposed from the surface of the substrate.
In the present invention, after high-pressure annealing, annealing is preferably performed under atmospheric pressure or low pressure.
In this method, the insulating layer-forming metal film includes, for example, tantalum (Ta) or a tantalum alloy.
In the present invention, the insulating layer includes, for example, an oxide film formed on the metal layer side by using the insulating layer-forming metal film, and an insulating film formed on the semiconductor layer side by using a semiconductor material having the same composition as the semiconductor layer. Namely, with the semiconductor layer including silicon, the insulating layer includes a silicon oxide film or a silicon nitride film formed on the semiconductor layer side.
In the present invention, at least the insulating layer side of the metal layer may include the same metal material as the insulating layer-forming metal film or a different metal material from the insulating layer-forming metal film.
The semiconductor device having the above construction can be manufactured by a method in which only the surface of the insulating layer-forming metal film is oxidized by high-pressure annealing to form the oxide film used as a part of the insulating layer, the remainder of the insulating layer-forming metal film being used as the metal layer or a part of the metal layer, or a method in which the insulating layer-forming metal film is entirely oxidized by high-pressure annealing to form the oxide film used as a part of the insulating layer.
In the present invention, the metal layer, the insulating layer and the semiconductor layer may be laminated in that order from the lower layer side to the upper layer side, or the semiconductor layer, the insulating layer and the metal layer may be laminated in that order from the lower layer side to the upper layer side.
The semiconductor device having this construction can be manufactured, for example, by a method including forming the metal layer below the insulating layer-forming metal film, annealing the insulating layer-forming metal film under high pressure, and then forming in turn the insulating layer including the same semiconductor material as the semiconductor layer in that order on the oxide film of the insulating layer-forming metal film and the semiconductor layer. The semiconductor device of the present invention can also be manufactured by a method including forming the semiconductor layer and the insulating layer including the same semiconductor material as the semiconductor layer below the insulating layer-forming metal film, annealing the insulating layer-forming metal film under high pressure, and then forming the metal layer on an oxide film of the insulating layer-forming metal film.
In the present invention, the MIS-type semiconductor element is, for example, a thin film transistor.
By using a semiconductor substrate as the substrate, not only a thin film transistor but also a bulk-type MIS transistor can be formed as the MIS-type semiconductor element. Namely, an insulating film including the same semiconductor material as the semiconductor substrate used as the substrate is formed on the semiconductor substrate, the insulating layer-forming metal film is formed and annealed under high pressure, and then the metal layer is formed on an oxide film of the insulating layer-forming metal film.
In the present invention, a MIS diode can be formed as the MIS-type semiconductor element.
In the present invention, a capacitor may include at least an oxide film formed as a dielectric film by using the same layer as an oxide film of the insulating layer-forming metal film, and the metal layer used as one of electrodes.
This semiconductor device can be formed, for example, as an active matrix substrate used for an electro-optic device, such as an active matrix liquid crystal device or the like. In this case, the thin film transistor is used as a pixel switching nonlinear element on the substrate. In the present invention, preferably a storage capacitor includes at least an oxide film formed as a dielectric film by using the same layer as the oxide film of the insulating layer-forming metal film, and the metal layer used as one of electrodes.
An electro-optic device of the present invention can be used as a display section of an electronic apparatus such as a cellular phone, a mobile computer, or the like. An electro-optic device of the present invention can also be used as a light valve of a projection display device (electronic apparatus).